Alpha Bull or VSS Vintorez

Well today I found a VSS Vintorez in Eastmore Apts. and know I'm debating with myself and can't decide from an Alpha or VSS

So exactly which weapon is better. They both have good DPS, but the Alpha is like 1 point better and has a very high critical.
I have no idea from which one to choose. I'm going for a critical build so yeah which is better and why.

Should I use the VSS, or the Alpha, or BOTH

The Alpha is agreed to be utterly superior.

Alpha is better. Also works with more builds.

Alpha Bull, plzkthx.